Design Close Focus Adapter for Box Camera?

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mh2000

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I've been playing around with a Brownie Target Six-16 box camera and would like to design a push-on closeup lens for the thing. I can't find the equations etc. online. Anyone have any idea how to do it?

From DOF tools, I'm guessing the camera has a fixed focus distance of ~15ft (gives around 10-50ft DOF now, FL=100mm @ f16?)). I'd like to get something giving focus from 6-10ft.

I have a No. 7A "portrait attachment," but haven't used it since it gives a focus distance of 3.5ft with very little DOF.

thanks!
 
I imagine the biggest challenge would be physically mounting the closeup lens. I haven't used closeup lenses, but I believe there are some in a variety of strengths, with names like "Proxar" (and others). Maybe you could try out the idea by getting one in a very mild strength and mounting on the camera temporarily, such as in a cardboard tube, to see the effect. Or could you extend the camera's lens further out from the film?
 
I’d just mount the closeup lens temporarily were you envision it would be in your final incarnation, put a piece of wax paper on the film plane held taught with some masking tape, set the camera to its “time” exposure setting and check focus with a loupe or 50mm lens. A tape measure and a contrasty focus target should give you a good idea where acceptable focus with both f-stops lies.
 
The problem I see with the ground glass approach is that with a max aperture of f16 it will be kind hard to nail down the actual focus distance, but as last resort I'll go with it. How to pick lens design and focal length? What's best? I'm putting together a 3d printer, so a slip-in lens barrel shouldn't be hard to fashion. The correct portrait lens for the camera is too close! The camera doesn't lend itself to much modification: it's crappy wood on the inside! And the shutter and aperture are in front of the lens.
 
so it looks like I can use the basic thin lens eq.:

1/u + 1/v = 1/f

Coupled with the two element focal length eq.:

1/f1 + 1/f2 = 1/F

to figure out a focal length of diopter to shift my focus to that desired.

At lease a rough approx.

Think I'll shoot some photos and not do any maths tomorrow though! 🙂
 
For a 6 to 10 ft. distance you need a hard to source +.5 diopter (focal length 2 meters or about 80 inches) With this lens on the camera prime focus will be roughly 6 ft. or a bit more. Don’t worry about the ground glass confirmation, as suggested at f16 it would be too hard to confirm.
If you know a friendly optometrist get him to order you a .5 positive diopter lens with a diameter of 50mm and tape it over the lens. Use a ring cut from cardboard to fill in the distance if the camera lens has a protruding bezel.

Edit: Or, just get a Zeiss 6x9 box camera that has close up lenses built in that can be rotated into place as needed.
 
I have the Zeiss 54/2 Box Tengor and a Clack! The reason I'm working with the Target Brownie Six-16 is because I want to shoot in the 616 postcard format and my attempt to get a Kodak Senior Six-16 folder to work failed because of the terrible Kodak bellows and unreliable shutters! I could get Box Tengor 54/15, but my experience with their little ground glass viewfinders is not very good! I couldn't get through my first roll of film in the 54/2 because I couldn't see a flipping thing outdoors! Agfa made some 616 (D6) box cameras, but they have ground glass viewfinders. The large brilliant viewfinders on the Brownie Targets are very usable, even with my bad eyes!
 
mh2000 said:
I have the Zeiss 54/2 Box Tengor and a Clack! The reason I'm working with the Target Brownie Six-16 is because I want to shoot in the 616 postcard format and my attempt to get a Kodak Senior Six-16 folder to work failed because of the terrible Kodak bellows and unreliable shutters! I could get Box Tengor 54/15, but my experience with their little ground glass viewfinders is not very good! I couldn't get through my first roll of film in the 54/2 because I couldn't see a flipping thing outdoors! Agfa made some 616 (D6) box cameras, but they have ground glass viewfinders. The large brilliant viewfinders on the Brownie Targets are very usable, even with my bad eyes!
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I don't recall how much of a front ring those Six-16s had, but you might find something in a push-on that would work. Or maybe a Series adapter in size IV or V.


PF
 
farlymac said:
I don't recall how much of a front ring those Six-16s had, but you might find something in a push-on that would work. Or maybe a Series adapter in size IV or V.


PF
Click to expand...

Kodak made a lot of un-spec'd closup/portrait lenses. I might be able to guess roughly what the diopter strength of some of them are and then adapt them to the camera.

An alternative would be get a Six-16 Brownie Special which has two zone focusing built in, but only a single aperture. The other complication is that the Special has a curve film plane, so I need to make a supporting mask. In the standard Brownie, the film doesn't need a masking support, so you get essentially the original format of the camera, albeit with film numbers and markings at the edges, but I kind of like the lomo/artiness of that! 🙂
 
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